Polyester resins and processes for preparing same

ABSTRACT

Magnesia having an iodine number greater than 100, a particle size of 0.4-3 microns, and containing about 86-96 weight percent of MgO for use as a chemical thickening agent in polyester resin systems.

United States Patent Inventors William H. Deis Belmont; Wesley WernerNess, San Bruno; Gerald Bohm, Sacramento, all of Calif. Appl. No. 9,092Filed Feb. 6, 1970 Patented Sept. 28, 1971 Assignee Merck & Co., Inc.

Rahway, NJ. Continuation of application Ser. No. 3 M51 Q9- L!? ew 3!@q0@-,

POLYESTER RESINS AND PROCESSES FOR PREPARING SAME 4 Claims, No DrawingsUS. Cl

[51] Int. Cl C08k 1/06 [50] Field of Search 260/40; 106/306 [56]References Cited UNITED STATES PATENTS 2,628,209 2/ 1953 Fisk 260/403,131,148 4/1964 Taulli 252/28 3,467,719 9/1969 Raichle et al 260/40Primary ExaminerMorris Liebman Assistant ExaminerS. M. Person a.EQPEXYQUS a!!! l-i remq a v a 86-96 weight percent of MgO for use as achemical thickening agent in polyester resin systems.

POLYESTER RESINS AND PROCESSES FOR PREPARING SAME This application is acontinuation of application Serial No. 587,658, now abandoned.

This invention concerns a novel form of magnesia, a novel polyesterresin system containing said magnesia, and a process for preparing saidnovel polyester resin system. More particularly, this invention concernsa polyester resin system which undergoes a rapid increase in viscosityat ambient temperature, a method for preparing this resin system, andthe particular magnesia useful in preparing such a resin system.

Polyester resins find use in the preparing of various articles ofmanufacture such as appliances, boats, automotive parts, and devices forelectrical equipment. During the preparation of such articles, it hasbeen found desirable to impart additional physical properties to thepolyester resin used so as to permit efficient and technically superiorproduction techniques. The use of a polyester-magnesia composition whichrapidly increases in viscosity is an important factor in permitting thedesired production techniques. The more rapid increase of viscositypermits the resulting thickened polyester to be used sooner after mixingand thereby reduces the amount of material held in inventory; thisaffords production economies. It is known in the art to use magnesia toincrease the viscosity of polyester resins. This invention is concernedwith compositions and procedures for improving the rate of viscosityincrease in polyester resins thickened with magnesia. This improved rateof viscosity increase is an important aspect of the present invention.

lt is an aspect of this invention to provide magnesia of a nature suchthat its addition to polyester resin causes a surprisingly rapidviscosity increase in the composition obtained. A further object isprovision of a method of making a polyester composition having improvedproperties. It is another object of this invention to provide animproved polyester composition containing magnesia specially suited toinsure a surprisingly beneficial viscosity-time relationship. Otherobjects will become apparent from the following description of the invention.

In accordance with this invention, there is prepared a novel magnesia ofparticle size and surface characteristics not heretofor available. Themagnesia of this invention is preparable from material having the samechemical composition but of significantly different particle size andsurface area. The novel magnesia of the desired particle size andporosity may be prepared from Maglite D 3231, a grade of magnesiaavailable from the Marine Magnesium Division of Merck & Co., Inc. Thismaterial has the following typical analysis: magnesium oxide, 92.84weight percent; ignition loss, 4.86 weight percent; carbon dioxide, 4.86weight percent; combined water, 4.62 weight percent; calcium oxide, 0.55weight percent; silicon dioxide, 0.27 weight percent; chloride, 0.17weight percent; sulfate, 0.68 weight percent; iron oxide, 0.03 weightpercent; aluminum oxide, 0.10 weight percent; manganese, 0.0020 weightpercent; copper, 0.0002 weight percent; acid insoluble, 0.05 weightpercent. The magnesia starting material may be jet milled using standardjet mill equipment such as a Fluid Energy and Equipment Co. Jetomizer.This starting material is then forced through the .letomizer at apressure of about 90 p.s.i.g. to produce the novel magnesia of thisinvention. Dry air at about 500 F. is used to provide the desiredpressure.

In accordance with this invention, the novel magnesia has a large andparticularly active surface. When measured by use of the standardwell-known test, the surface area of this novel magnesia has an iodinenumber greater than 100. It will be understood that iodine memberrepresents the number of milliequivalents of iodine adsorbed per hundredgrams of magnesia sample.

The novel magnesia here found to impart desirable physical properties topolyester resins compositions is possessed of an average particle sizein the order of about 0.1-7 microns, preferably 0.4-3 microns, and stillmore preferable 0.4-1.2 microns. Any standard and accurate method issuitable in ascertaining the particle size. For instance, the ultracentrifuge technique using a Mine Safety Appliance Co. Whitby Centrifugemay be successfully utilized. Such method of measuring particle size iscommonly known as the MSA-Whitby method for particle size determination.

lt has also been found in accordance with this invention that magnesiahaving certain quantities of individual chemical components is suited toprovide polyester resins with the desired viscosity characteristics. Themagnesia with which this invention is concerned is 86-96weight percentpure magnesium oxide. However, it is preferred that the particle ofmagnesia utilized contain about 89-rweight percent pure magnesium oxide.The magnesia of this invention also contains 1.5-1 1.5 weight percent ofcombined water, preferably 3.5-8.5 weight percent.

The preferred bulk density for the novel magnesia of the presentinvention is 5-14 pounds per cubic foot, the preference being for thepurposes of transportation and handling, rather than the effect upon thepolyester Consequently, such bulk density is in no way a critical aspectof this invention.

In accordance with an additional aspect of this invention, the novelmagnesia above described is blended with polyester resin. About 0.2-10weight percent and preferably 0.4-3 weight percent of magnesia may beemployed. The resulting material, a thickened polyester resin, hasdesirable physical characteristics, particularly the ability to attainhigh viscosity in a relatively short time. For instance, certain of thethickened polyester resins of the present invention attain viscositiesof poise at room temperature in about 24 hours, whereas otherwiseidentical thickened polyesters containing other magnesias may requireabout 5 days to attain this same viscosity. Moreover, certain of thethickened polyesters of the present invention permit the obtaining ofviscosities of about 10,000 poise without addition of any filler,whereas otherwise identical thickened polyesters containing the sameweight percent of ordinary magnesia are incapable of attaining thisviscosity at all, particularly without the addition of large quantitiesof sometimes undesirable filler.

The novel compositions of matter which are here called thickenedpolyesters are particularly useful in the preparation of objects andarticles of manufacture where low tackiness and smooth finishes aredesired. The composition may also contain fillers such as are normallyused in the art for making articles prepared from polyesters. Suchfillers include barytes, ground silica, magnesium carbonate, ditamaceousearth, glass fiber, hydrated alumina, and the like.

The magnesia is conveniently incorporated into polyester resin byintimately admixing it with the polyester using a highspeed, high-shearmixer. The magnesia may also be admixed to a vehicle to form adispersion. A Cowles Dissolver is useful in preparing such dispersion. Adry form of the magnesia may also be added to the polyester. Themagnesia is readily admixed with the polyester using a laboratorystirrer operating at about 4-6,000 revolutions per minute. The entiremixing procedure may take place at room temperature.

The polyester starting materials employed in this invention arepolymerizable resin compositions derived from the product obtained bydissolving a precondensed linear polymer in a monomeric polymerizablecompound containing an ethylenic bond and capable of cross linking thelinear polymer into a rigid three-dimensional gel. The linear polymer isa polymeric ester produced by the recurring condensation of adicarboxylic acid (aromatic or ethylenic) with a polyol such aspropylene glycol or glycerol. The monomeric polymerizable compound usedfor cross linking contains an ethylenic grouping, preferably attached toa phenyl group as in styrene, alphamethyl styrene or divinyl benzene. Asexamples of some of the resins within the above description there may bementioned Stypol 40-2417 (Freeman Chemical Co.); Selectron RS 5003,Selectron 5156, Selectron 50012, Selectron RS 5119 (Pittsburg PlateGlass Co.); Plaskon 9520 (Allied Chemical Co.); and the like.

When admixed with the novel magnesia of the present invention, the abovepolyesters provide a composition having enhanced physical propertiesparticularly beneficial in the production of various articles ofmanufacture. This composition is of sufl'tciently low viscosity shortlyafter preparation to completely wet a filler. Thereafter, the novelpolyester-mag nesia composition becomes highly viscous, permitting easyhandling, ready storage and convenient use ofdirect molding techniques.The obtaining of this highly viscous thickened polyester at an enhancedrate permits substantial savings of both time and expense during thepreparation of the molded articles.

The reason for the surprising viscosity increase in the thickenedpolyester resin is not clearly understood. Although we do not wish to bebound by the theory involved, it is believed that physical phenomena,such as colloidal effects or gelling, imparts some of the unusualviscosity characteristics to the thickened polyester compositions ofthis invention.

The following examples are given for the purpose of illustration and notby way oftimitation:

EXAMPLE l The novel magnesia of the present invention (2 percent byweight) is blended with the polyester resin, Stypol 40-2417, by use of alaboratory stirrer operating at 5,000 revolutions per minute. Forconvenience, the magnesia may be dispersed in a nonreactive vehicle suchas a plasticer before addition to the polyester, although this is notessential.

The novel magnesia used had an average particle size of 3 Type ofmagnesia.

It will be seen that the polyester containing the novel magnesia hassubstantially greater viscosity than that prepared from magnesiaoflargcr particle size and smaller surface area.

EXAMPLE 2 The novel magnesia of this invention and Type B magnesia areintimately blended as in example 1 with a polyester commercially knownas Plaskon 9520 manufactured by Allied Chemical Co. Two percent byweight of magnesia is employed. The novel magnesia has an averageparticle size of().6 microns and an iodine absorption number of 155whereas the Type B magnesia has a particle size of 13 microns and aniodine absorption number of 135. The following viscosities are measuredafter the indicated number of days after blending.

Table ll 0 Days at Ambient Tem It is clear from the above example thateven with magnesia of comparable surface area, the larger particle sizereduces the desired beneficiat viscosity buildup.

EXAMPLE 3 TABLE III Weight percent; magnesia in resin Viscosity, poiseNovel Novel magnesia Type 13" magnesia Type B HOHZTS at ambienttemperature:

Viscosity, Poise Hours After lending Novel Magnesia Type A Mngncsio (l8.5 son .120 7 21 7,700 4,5 70

EXAMPLE4 The magnesia of the present invention and Type B magnesiumoxide discussed above are separately blended as in example l with eachof three different types of Sclectron polyester resins which wereobtained from Pittsburgh Plate Glass Co. ln each instance, 2.0 weightpercent of magnesia is used. The fol lowing table shows the resultsobtained for the indicated number of hours after the addition of themagnesium oxide to the resin.

The greater viscosity displayed by the magnesia-polyester compositionsusing the novel magnesia is clearly evident. in some instances, over afiftyfold increase in viscosity is shown over that obtainable with typeB magnesia.

TABLE IV Resin typo Selcetron RS 5003 Selectron 5156 Selection RS 511'.)

T ype of magnesia Novel nniguesia. typev ll, viscosity, poise Hours atambient.

temperature:

EXAMPLE 5 at designated times after blending. Results are shown in TableV.

TABLE V Type of magnesia, viscosity, poise Type A" Novel Type 0"magnesia magnesia magnesia Weight percent magnesia in resin. 1 1 2 1 2 12 Hours at ambient temperature:

EXAMPLE 6 Magnesium oxide containing 92.4 percent MgO, having an iodinenumber of 152 (m.eq./l00 g.), an average particle size of l8.5 microns(MSA Whitby method) and a loose bulk density of 24 pcf, is fed to a.letomizer Model 0405CC fluid-energy jet mill at a rate of 400 lbs/hour.Air preheated to 500 F. is passed through ajet into the mill at ajetpressure of 90 p.s.i.g. and at a rate of 550 s.c.f.m. (standard cubicfeet/minute). The

milled magnesia is collected in a cyclone and fed into a bin l'orpackaging. it contains 92.3 percent Mg(), has an iodine number of 150,an average particle size ol'0.47 microns and a loose bulk density of7p.c.f.

It should be understood that although this invention has been describedwith reference to particular embodiments thereof, changes andmodifications may be made which are within its intended scope and itshould be limited only by the language of the appended claims.

What is claimed is:

l. A composition of matter having improved physical propertiescomprising a polyester resin and 02-10 weight percent of jet-milledmagnesia having an iodine number greater than 100, prior to jet milling,a particle size of 0.1-7 microns, and containing about 86-96 weightpercent of MgO.

2. A composition of claim 1 characterized in that the polyester resin isone prepared from a dicarboxylic acid, a polyol and a monomericpolymerizable compound containing an ethylenic bond, and in that thecomposition contains 0.4-3 weight percent of magnesia having an iodinenumber greater than 100, a particle size of 0.4-1.2 microns, andcontaining about 89-94 weight percent of MgO.

3. A process for preparing the composition of claim 1 that comprisestreating a polyester resin with 0.2-l0 weight percent of magnesia havingan iodine number greater than I00, a particle size of 0.4-3 microns, andcontaining about 86-96 weight percent of MgO.

4. A process for preparing the composition of claim 2 that comprisestreating a polyester resin prepared from a dicarboxylic acid, a polyoland a monomeric polymerizable compound containing an ethylenic bond,with 0.4-3 weight percent of magnesia having an iodine number greaterthan 100, a particle size of 0.4-1.2 microns, and containing about 89-94weight percent of MgO.

2. A composition of claim 1 characterized in that the polyester resin isone prepared from a dicarboxylic acid, a polyol and a monomericpolymerizable compound containing an ethylenic bond, and in that thecomposition contains 0.4-3 weight percent of magnesia having an iodinenumber greater than 100, a particle size of 0.4-1.2 microns, andcontaining about 89-94 weight percent of MgO.
 3. A process for preparingthe composition of claim 1 that comprises treating a polyester resinwith 0.2-10 weight percent of magnesia having an iodine number greaterthan 100, a particle size of 0.4-3 microns, and containing about 86-96weight percent of MgO.
 4. A process for preparing the composition ofclaim 2 that comprises treating a polyester resin prepared from adicarboxylic acid, a polyol and a monomeric polymerizable compoundcontaining an ethylenic bond, with 0.4-3 weight percent of magnesiahaving an iodine number greater than 100, a particle size of 0.4-1.2microns, and containing about 89-94 weight percent of MgO.